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Allergens: Poison Ivy/Poison Oak/Poison Sumac

What is poison ivy, poison oak, or poison sumac?

There are three native American plants that collectively may be called poison ivy: poison ivy, poison oak, and poison sumac. These plants cause an allergic reaction in nearly 85 percent of the population. To be allergic to poison ivy, you must come in contact with the plant once for sensitization to the oils to occur. This means that next time contact with the plant occurs, a reaction may occur.

What causes the allergic reaction?

The resin in the plants contains an oily substance called urushiol. Urushiol is easily transferred from the plants to other objects, including tools and animals. This chemical can remain active for a year or longer. It is important to know that the oils can be transferred from clothing, pets, or smoke from a burning plant.

What is the allergic reaction?

The reaction is usually contact dermatitis, which may occur several hours, days, or even weeks after exposure. The dermatitis is characterized by a rash followed by bumps and blisters that itch. Sometimes, swelling occurs in the area of contact. Eventually, the blisters break, ooze, and then crust over.

Treatment for poison ivy, poison oak, or poison sumac

There in no cure for poison ivy once the rash starts. Avoiding the poison plants is the best treatment. It is very important to learn what the plants look like and not to touch them.

If contact with the plants has already occurred, you should remove the oils from the skin as soon as possible by cleansing with an ordinary soap. Repeat the cleaning with the soap three times. There are also alcohol-based wipes that help remove the oils. Wash all clothes and shoes also because the oils can remain on these.

For the itching, your doctor may recommend over-the-counter creams, such as calamine lotion or bathing in a baking soda or colloidal oatmeal bath (can be bought at your local drugstore). Sometimes, your doctor will prescribe a medication by mouth for the itching.

If you have a temperature over 100 degrees F (38 degrees C), and the blisters and rash are on the face, spread to your eyes, near the genitals, or all over the body, your doctor should be notified. After a thorough history and physical, your doctor may prescribe a steroid cream or injection to help with the swelling and itching.

Is poison ivy, poison oak, or poison sumac contagious?

No. It can not be spread from person to person by touching the blisters or from the fluid inside the blisters. It can be spread, however, if the oils remain on the skin, clothes, or shoes. This is why washing your hands, clothes, and shoes as soon as possible is very important.